Composite electronic components

ABSTRACT

A dielectric coating, a solid electrolytic layer and a collector layer are provided to one face of a porous valve metal sheet. An insulating section covers this metal sheet including the layers discussed above. Conductive bodies, which are coupled with a first connecting terminal and a second connecting terminal, respectively, are surfaced on at least one face of the insulating section. Connecting bumps are formed on these conductive bodies, so that ICs and other parts are coupled with these bumps. This structure realizes a thin composite electronic component having an excellent high-frequency response.

TECHNICAL FIELD

The present invention relates to a composite electronic component to beused in various electronic apparatuses.

BACKGROUND ART

A conventional composite electronic component comprises an integratedcircuit (IC), a capacitor, an inductance, and a resistor placed on acircuit board. In such a conventional composite electronic component, acapacitor is mounted on a circuit board as a solid electrolyticchip-capacitor in the same manner as other parts such as resistors andinductance parts.

Electronic circuits have been digitized recently in response to themarket's demand, and this tendency involves high-frequency responses ofelectronic parts. A wiring is usually accompanied by a resistancecomponent and an inductance component, and those components have notbeen raised as a problem. However, such components now block the solidelectrolytic capacitor, which is surface-mounted on a circuit boardtogether with an IC, from responding fast to a high-frequency.

SUMMARY OF THE INVENTION

The present invention aims to overcome the foregoing drawback andprovide a thin composite electronic component having an excellent inhigh-frequency response and being directly bump-connectable to an IC.The composite electronic component of the present invention comprisesthe following elements: a capacitor element; an insulating section forcovering the capacitor element; a connecting terminal, provided to atleast one face of the insulating section, for electrically coupling withthe capacitor element; a plurality of wiring patterns, provided to thesame face as the connecting terminal, for conducting with electroniccomponents; and outer terminals, provided to lateral faces of theinsulating section, for electrically coupling with the capacitorelement.

The capacitor element of the composite electronic component includes thefollowing elements: a first connecting terminal provided to a porousvalve metal sheet which has dielectric coating on both its surface andthe inner wall of its void holes; a second connecting terminal providedto the porous valve metal sheet via a solid electrolytic layer at theface opposite to the first connecting terminal; holes at leastcommunicating with the first connecting terminal and the secondconnecting terminal, the hole having an insulating film on its innerwall; and conductive bodies formed in the holes, and the conductivebodies being electrically connected with the first and second connectingterminals but insulated from other sections.

The connecting terminals are thus formed on the surface of the thincapacitor, and various chip parts including an IC can be mounted via theconnecting terminals so that high-frequency response is substantiallyimproved. At the same time, the composite component is downsized andthinned.

BRIEF DESCRIPTIONS OF THE DRAWINGS

FIG. 1 shows a sectional view of a composite electronic component inaccordance with an exemplary embodiment of the present invention.

FIG. 2 shows an enlarged sectional view illustrating an essential partof the composite electronic component in accordance with an exemplaryembodiment of the present invention.

FIG. 3 shows a sectional view of a porous valve metal sheet to be usedin the composite electronic component shown in FIG. 1.

FIG. 4 shows a sectional view of the porous valve metal sheet on which afirst connecting terminal is formed.

FIG. 5 shows a sectional view of the porous valve metal sheet, shown inFIG. 4, where an insulating section is additionally formed on the sheetincluding the first connecting terminal.

FIG. 6 shows a sectional view of the porous valve metal sheet, shown inFIG. 5, where a dielectric coating and a solid electrolytic layer areadditionally formed.

FIG. 7 shows a sectional view of the porous valve metal sheet, shown inFIG. 6, where a collector layer is additionally formed.

FIG. 8 shows a sectional view of the porous valve metal sheet, shown inFIG. 7, where holes are additionally formed.

FIG. 9 shows a sectional view of the porous valve metal sheet, shown inFIG. 8, where a second connecting terminal is additionally formed.

FIG. 10 shows a sectional view of the porous valve metal sheet, shown inFIG. 9, where an insulating section is additionally formed including thesecond connecting terminal.

FIG. 11 shows a sectional view of the porous valve metal sheet, shown inFIG. 10, where an insulating film is formed in the holes.

FIG. 12 shows a sectional view of the porous valve metal sheet, shown inFIG. 11, where holes are additionally provided to the insulating sectionon the first connecting terminal.

FIG. 13 shows a sectional view of the porous valve metal sheet, shown inFIG. 12, where a conductive body is formed in the respective holes.

FIG. 14 shows a sectional view of the porous valve metal sheet, shown inFIG. 13, where a connecting bump is additionally provided to therespective conductive bodies.

FIG. 15 shows a sectional view of the porous valve metal sheet, shown inFIG. 14, where outer terminals are additionally provided.

FIG. 16 shows a sectional view of the porous valve metal sheet, shown inFIG. 15, where a wiring pattern is formed and electronic parts and ICsare mounted thereon.

FIG. 17 shows a sectional view of a porous valve metal sheet inaccordance with a second exemplary embodiment of the present invention.

FIG. 18 shows a sectional view of a porous valve metal sheet inaccordance with a third exemplary embodiment of the present invention.

DETAILED DESCRIPTIONS OF EXEMPLARY EMBODIMENTS

The exemplary embodiments of the present invention are demonstratedhereinafter with reference to the accompanying drawings. The drawingsillustrate essential parts of the invention in order to demonstratepoints of the invention and, therefore, dimensions of the elements arescaled down differently from the actual ones.

Exemplary Embodiment 1

FIG. 1 shows a sectional view of a composite electronic component inaccordance with the first exemplary embodiment of the present invention.FIG. 2 shows an enlarged sectional view illustrating an essential partof the composite electronic component.

Electronic component 16 shown in FIG. 1 has a thickness of the order ofseveral millimeters and, on the other hand, solid electrolytic capacitorelement 200 has a thickness of the order of sub-millimeters. FIG. 1enlarges, in particular, the capacitor element. An etched section hasactually a complicated irregular shape on its surface, however,simplified pits are shown in FIG. 2 instead.

The composite electronic component shown in FIG. 1 and FIG. 2 comprisesthe following elements:

(a) a porous valve metal sheet 1 made from aluminum foil of which oneface is etched, or made of sintered body of valve metal powder such astantalum; and

(b) a first connecting terminal 2 provided to one face of the sheet 1.

In the case of aluminum foil being used, the unetched face can beutilized as first connecting terminal 2, or a layer of another metalsuch as gold, copper or nickel can be formed on the unetched face of thealuminum foil. In the case of the sintered body of the valve metalpowder being used, a face to which the sintered body is mounted and nodielectric coating is formed can be utilized as a first connectingterminal 2, or a layer of another metal such as gold, silver, nickel ortantalum can be formed by a spattering method or a vapor depositionmethod.

Anodizing the porous valve metal sheet 1 except the first connectingterminal 2 forms a dielectric coating 3 on the metal surface. A solidelectrolytic layer 4 can be formed on dielectric coating 3 by chemicalpolymerization or electrolytic polymerization of a functional polymerlayer made of e.g., polypyrrole or polythiophene. Solid electrolyticlayer 4 can be also obtained by forming a manganese dioxide layerthrough impregnating manganese nitrate into dielectric coating 3 andpyrolytically decomposing it.

Further on solid electrolytic layer 4, a collector layer 5, made bylaminating only carbon layers or carbon layers together with conductivepaste layers, is formed.

In this first embodiment, a second connecting terminal 6 facing firstconnecting terminal 2 is formed on the collector layer 5 by spatteringgold. Another metal such as copper, nickel or tantalum instead of goldcan be vapor-deposited or spattered. The collector layer 5 as it is canbe utilized as the second connecting terminal.

The body formed hitherto is covered overall with insulating material sothat an insulating section 7 is formed. Then, a hole 8 is formed whichextends through insulating section 7 on first connecting terminal 2 sideand communicates with the first connecting terminal 2. Further, anotherhole 9 is formed which extends through the insulating section 7 on firstconnecting terminal 2 side, the first connecting terminal 2, the porousvalve metal sheet 1, the dielectric coating 3, the solid electrolyticlayer 4 and the collector layer 5, and communicates with the secondconnecting terminal 6. Holes 8 and 9 are formed by etching, punching orlaser processing.

On the inner wall of hole 9, the insulating film 10 is formed byelectro-deposition process of an insulating material. Then conductivebodies 101 and 111 made from copper plate are formed in holes 8 and 9.The conductive body 101 in hole 8 is electrically conductive with onlythe first connecting terminal 2, and conductive body 111 in hole 9 iselectrically conductive with only second connecting terminal 6.

On the surfaces of conductive bodies 101 and 111, connecting bumps 12,made from solder, gold, tin or silver, are formed as surface connectingterminals, so that the solid electrolytic capacitor element 200 iscompleted. A number of, and a placement of, connecting bumps correspondto those of the ICs to be mounted thereto. A number of bumps more thanthe number of the ICs can be formed because chip components such as achip inductance can be mounted between the bumps 12 which remain afterthe mounting of the ICs. On the insulating section 7 on the lateralfaces and the bottom face of solid electrolytic capacitor element 200,an outer terminal 13 coupled with the first connecting terminal 2 aswell as an outer terminal 14 coupled with the second connecting terminal6 is formed.

Finally, electronic parts 16 such as chip-resistors, chip-ceramiccapacitors, chip-inductances, ICs and the like are coupled with wiringpatterns 15 so that a composite electronic component is produced. Assuch, ICs 17 and the like can be mounted directly to one of the faces ofthe thin solid electrolytic capacitor, so that a conductive pattern forwiring is not needed. As a result, high-frequency response can beremarkably improved, and since the thin solid electrolytic capacitor isequipped with electronic circuit parts 16, a thin composite electroniccomponent is obtainable.

In the first embodiment, an aluminum foil, of which one side has beenetched, is used as the porous valve metal sheet 1. Thus the aluminumfoil of the aluminum electrolytic capacitor available in the market canbe utilized. If a face of the aluminum foil is masked and then etched, aporous valve metal sheet 1 having desirable etching pits on only oneface can be obtained with ease. This method increases the productivityof the composite electronic components. When a sintered body of a valvemetal powder such as tantalum is used as the porous valve metal sheet 1,a large electrostatic capacity can be obtained.

The use of one face of the aluminum foil or sintered body of the valvemetal powder as the first connecting terminal 2 eliminates the need fora metal layer which is supposed to be a separate first connectingterminal, so that the productivity can be improved as well as the costcan be reduced. However, if the reliability of the connection betweenconductive bodies 101, 111 formed in holes 8, 9 and the first connectingterminal 2 is desirably increased, first connecting terminal 2 ispreferably formed by forming a metal layer of gold, copper or nickel onone face of the sheet 1.

A use of functional polymers such as polypyrrole or polythiophene assolid electrolytic layer 4 produces a solid electrolytic capacitorhaving a lower impedance, which is excellent in high-frequency response.Forming manganese dioxide is an well established method, and this methodallows elaborate control even over a thickness. A use of this methodthus improves the productivity and reliability. Outer terminals 13, 14are not always necessarily, and they can be replaced with connectingbumps 12 or wiring patterns 15. The ICs and chip parts mounted toconnecting bumps 12 are used as leader-electrodes.

A method of manufacturing the solid electrolytic capacitor of thepresent invention is demonstrated hereinafter with reference to theaccompanying drawings. First, as shown in FIG. 3, an aluminum foil isprepared, of which one face has been etched, as a porous valve metalsheet 1. This aluminum foil is obtainable with ease by masking one facebefore the etching process. In FIG. 3, the etched shape to be formed onsheet 1 is omitted.

Next, as shown in FIG. 4, on the unetched face of sheet 1, a firstconnecting terminal 2 made from copper is formed by spattering. Terminal2 can be also formed by vapor-deposition or sticking copper foil to theunetched face.

Then as shown in FIG. 5, sheet 1 is covered, except the etched face,with thermosetting polyester resin, thereby forming insulating section7.

In this first embodiment, molding resin made of a thermosetting epoxyresin and an inorganic filler is transfer-molded, thereby forminginsulating section 7. Instead of the thermosetting epoxy resin,photo-curable epoxy resin, thermosetting or photo-curable unsaturatedpolyester resin can be used as the insulating resin. A method ofapplication can be used instead of the transfer-molding method.

Next, metal aluminum is anodized in forming solution to form adielectric coating 3 on the surface of the metal as shown in FIG. 6.Then the metal is dipped into solution including pyrrole, and thendipped into oxidizing solution so that a thin polypyrrole film is formedon the dielectric coating 3 due to chemical oxidation polymerization.After the formation of polypyrrole thin film, the metal aluminum isdipped into solution containing pyrrole, and the polypyrrole layer isused as an anode side and an electrode in the solution is used as acathode side for performing electrolytic polymerization. Thiselectrolytic polymerization forms a polypyrrole layer having enoughthickness on the thin polypyrrole layer. A solid electrolytic layer 4 isthus produced.

Next, as shown in FIG. 7, carbon ink is applied on the solidelectrolytic layer 3 and the carbon ink is dried. Next, silver paint isapplied and hardened thereby forming a collector layer 5 made of acarbon layer and a silver paint layer. Then as shown in FIG. 8,through-holes 9 are punched at necessary places.

Next, as shown in FIG. 9, a second connecting terminal 6 made of copperis provided to the collector layer 5 so that the terminal 6 iselectrically conductive with collector layer 5. Then as shown in FIG.10, an insulating section 7 made of thermosetting epoxy resin isextended such that it covers the second connecting terminal 6, solidelectrolytic layer 4 and the surface of the collector layer 5. As aresult, the entire body is covered by the insulating section 7. Afterthat, as shown in FIG. 11, insulating film 10 made of resin is formed onthe inner wall of hole 9 by an electrode-position process.

As shown in FIG. 12, hole 8 is formed by laser process at apredetermined place on the terminal 2, and openings 52, 53 communicatingwith lateral faces of first terminal 2, and second terminal 6,respectively, are formed. Then, conductive bodies 101, 111, 121 and 131made from a copper plate are formed in holes 8, 9 and openings 52, 53,respectively. The conductive body 101 in hole 8 and the conductive body121 in opening 52 are electrically coupled with the first connectingterminal 2. The conductive body 111 in hole 9 and the conductive body131 in hole 53 are electrically coupled with the second connectingterminal 6.

Further, as shown in FIG. 14, surface connecting terminals 12, i.e.connecting bumps made from solder, gold or silver, are formed on thesurfaces of the conductive bodies 101 and 111, thereby completing thesolid electrolytic capacitor element 200.

Then as shown in FIG. 15, outer terminals 13, 14 coupled with a firstconnecting terminal 2 and a second connecting terminal 6 via conductivebodies 121, 131, respectively, are formed on the lateral faces and thebottom face of the capacitor element 200.

Next, as shown in FIG. 16, wiring pattern 15, made of conductivematerial and corresponding to a circuit pattern, are formed on theinsulating section 7 on which connecting bumps 12 have been formed.Then, electronic components 16 including an inductance, resistors andthe like, as well as an IC 17, are connected to given places, therebyproducing a composite electronic component.

The present invention allows to substantially lower the inductance of anelectrical path between the capacitor and the IC, thereby improvinghigh-frequency properties.

Exemplary Embodiment 2

In the second embodiment, a valve metal powder is used instead of anetched aluminum sheet. As shown in FIG. 17, a sintered body 19 oftantalum is coupled with one face of a tantalum foil 18, thereby forminga porous valve metal sheet 1. The steps of forming the insulatingsection 7 and onward, in other words, the steps shown in FIG. 5 andonward, are the same as those demonstrated in the first embodiment. Asolid electrolytic capacitor is thus formed, and then a compositeelectronic component is produced.

In the first embodiment, as shown in FIG. 4, a first connecting terminal2 made from copper is formed by spattering on the unetched face of ametal sheet 1 made from aluminum foil. In this second embodiment, afirst connecting terminal 2 made from copper is formed by spattering onthe one face, where no sintered body 19 of tantalum is formed, of thetantalum foil 18 shown in FIG. 17. The steps shown in FIG. 5 and onwardare the same as those demonstrated in the first embodiment.

The completed composite electronic component has a dielectric, i.e.,tantalum oxide, of which a dielectric constant is greater than that ofaluminum oxide, thus the composite electronic component features notonly an excellent high-frequency response but also a capacitor having agreater capacity. The sintered body of tantalum is formed of tantalumparticles which can be finely divided for enlarging an effective area ofthe capacitor. Therefore, this structure allows an increase in both thedielectric constant and the capacity. As a result, a capacity as much asfour times greater than using the etched aluminum foil is obtainable.

Exemplary Embodiment 3

Instead of using etched aluminum sheet, another valve metal powder thanthe second embodiment is used in this third embodiment with reference toFIG. 18. First, the metal powder of tantalum is sintered and a poroustantalum sheet 19 is formed. Second, an insulating section 7 made ofthermosetting epoxy resin is formed on one face of the sheet 19. Next,the sheet 19 including insulating section 7 is anodized, thereby forminga dielectric layer over all the holes of porous sheet 19. The stepsafter this are the same as those in the first embodiment, i.e., thesteps shown in FIG. 6 and onward. A solid electrolytic capacitor is thusformed, and finally a composite electronic component is produced. Inthis third embodiment, the sintered body has a metal face 29 which iscovered by thermosetting resin, and the face 29 is not anodized butmaintains electric conductivity.

A first connecting terminal 2 made from copper can be formed byspattering on the metal face 29, where no dielectric layer of a tantalumsintered body 19 is formed, and an insulating section 7 can be formed onterminal 2. The steps after the anodizing are the same as thosedemonstrated in the first embodiment.

The completed composite electronic component has a dielectric, i.e.,tantalum oxide, of which a dielectric constant is greater than aluminumoxide, thus the composite electronic component features not onlyexcellent high-frequency response but also a capacitor having a greatercapacity. Further, since this structure does not employ metal sheet, athinner composite electronic component is obtainable.

INDUSTRIAL APPLICABILITY

The present invention relates to a composite electronic component to beused in various electronic apparatuses. According to the structure ofthe present invention, electronic parts are placed on a thin capacitor,so that ICs can be directly connected to one face of the thin capacitor.On the face, a connecting section is formed. Further, other parts can bemounted to the face, thereby forming a thin composite electroniccomponent useful for preparing a digital circuit as well as excellent inhigh-frequency response.

What is claimed is:
 1. A composite electronic component comprising: acapacitor element including; a porous valve metal sheet having a firstface of a porous surface and having a dielectric coating on the poroussurface; a first connecting terminal provided on a second face of saidporous valve metal sheet; a solid electrolytic layer provided on thedielectric coating; a second connecting terminal provided on said solidelectrolytic layer; an insulating section provided on said valve metalsheet, said first connecting terminal, and said second connectingterminal; a first hole extending through said insulating section andcommunicating with said first connecting terminal; a second holeextending through said insulating section and said porous valve metalsheet, communicating with said second connecting terminal, and havinginsulating film provided therein; and first and second conductive bodiesprovided in said first hole and said second hole, respectively, saidfirst and second conductive bodies being electrically coupled with saidfirst and second connecting terminals, respectively, and being insulatedfrom other sections; a surface connecting terminal provided on at leastone face of said insulating section and being electrically coupled withsaid capacitor element; a plurality of wiring patterns provided on thesame face as said surface connecting terminal; and first and secondouter terminals electrically coupled with said capacitor element at alateral face of said insulating section.
 2. The composite electroniccomponent of claim 1, further comprising a collector provided betweensaid second connecting terminal and said solid electrolytic layer. 3.The composite electronic component of claim 1, wherein said porous valvemetal sheet is made from aluminum foil having one face which is etched.4. The composite electronic component of claim 1, wherein said porousvalve metal sheet is made from a sintered body of a valve metal powder.5. The composite electronic component of claim 1, wherein said porousvalve metal sheet is made of a valve metal sheet on which a sinteredbody of the valve metal is provided.
 6. The composite electroniccomponent of claim 1, wherein said first connecting terminal is a firstface of aluminum foil having a second face which is porous due to anetching process.
 7. The composite electronic component of claim 1,wherein said first connecting terminal is another metal layer formed ona first face of aluminum foil having a second face which is porous dueto an etching process.
 8. The composite electronic component of claim 1,wherein said first connecting terminal is a face of said porous valvemetal sheet made of a sintered body of a valve metal powder, wherein theface has no dielectric.
 9. The composite electronic component of claim1, wherein said first connecting terminal is another metal layer formedon a face of said porous valve metal sheet made of a sintered body of avalve metal powder, wherein the face has no dielectric.
 10. Thecomposite electronic component of claim 1, wherein said first connectingterminal is a first face of a valve metal sheet, wherein a sintered bodyof a valve metal powder is provided on a second face of the valve metalsheet.
 11. The composite electronic component of claim 1, wherein saidfirst connecting terminal is another metal layer formed on a first faceof a valve metal sheet, wherein a sintered body of a valve metal powderis provided on a second face of the valve metal sheet.
 12. The compositeelectronic component of claim 1, wherein said solid electrolytic layeremploys a functional polymer.
 13. The composite electronic component ofclaim 1, wherein said solid electrolytic layer employs a manganesedioxide.
 14. The composite electronic component of claim 1, wherein anumber of said surface connecting terminal is greater than a number ofconnecting bumps provided on an integrated circuit.
 15. A method formanufacturing a composite electronic component, said method comprising:forming a capacitor element by: preparing a porous valve metal sheet byforming a porous surface and a dielectric coating on a first face of avalve metal sheet; forming a first connecting terminal on a second faceof the porous valve metal sheet; forming a solid electrolytic layer onthe dielectric coating; forming a second connecting terminal on thesolid electrolytic layer; forming an insulating section on the porousvalve metal sheet, the first connecting terminal, and the secondconnecting terminal; forming a first hole to extend through theinsulating section and to communicate with the first connectingterminal; forming a second hole to extend through the insulating sectionand the valve metal sheet, communicate with the second connectingterminal, and have insulating film provided therein; and providing firstand second conductive bodies in the first hole and the second hole,respectively, wherein the first and second bodies are provided so as tobe electrically coupled with the first and second connecting terminals,respectively, and to be insulated from other sections; providing asurface connecting terminal on at least one face of the insulatingsection and so as to be electrically coupled with the capacitor element;providing a plurality of wiring patterns on the same face as the surfaceconnecting terminal; and providing first and second outer terminals tobe electrically coupled with the capacitor element at a lateral face ofthe insulating section.
 16. The method of claim 15, further comprisingproviding a collector between the second connecting terminal and thesolid electrolytic layer.
 17. The method of claim 15, wherein the poroussurface of the valve metal sheet is made from aluminum foil having thefirst face etched.
 18. The method of claim 15, wherein the porous valvemetal sheet is made from a sintered body of a valve metal powder. 19.The method of claim 15, wherein the porous valve metal sheet is made ofa valve metal sheet on which a sintered body of the valve metal isformed.
 20. The method of claim 15, wherein the first connectingterminal is a first face of aluminum foil having a second face which isporous due to an etching process.